Boiler Condensation Module

ABSTRACT

The invention concerns a boiler condensation module, characterised in that it comprises a water/fume heat exchanger (E) and a closed circuit compression thermodynamic frigorific apparatus, said module ( 2 ) being communicated with a boiler ( 1 ) intercepting the flow of the fumes and the flow of the water, in order to subtract sensitive heat and vaporisation latent heat to the fumes of the boiler to yield the same as heat to the system water thus improving the combustion efficiency.

The present invention relates to a boiler condensation module.

More specifically, the invention relates to a device of the above kindthat, when installed inside, or connected with, a methane- or G.P.L.-,or Diesel oil-fed heating boilers, or with another kind of boiler, picksup the exhaust fumes from the combustion, positively exploiting theresidual heat.

At present, most used boilers are the so-called “high-efficiencyboilers”. These apparatuses can exploit up to a 95% of the combustiblecalorific power, loosing only 5% of the total heat. They are used forfeeding high temperature systems, i.e. systems employing standardradiators and/or fan coils, i.e. elements requiring, for a properoperation, a thermal vector (water) with temperatures above 70° C. Saidboilers cannot recover combustion latent heat of vaporisation, i.e. heatthat would be recovered transforming vapour produced during thecombustion into liquid form.

Some of the most important gas boiler manufacturers produce the“condensation boilers”, i.e. particular boilers that, by a normallyupset, particular burner, and one increased efficiency smoke/water heatexchanger, can bring the combustion fumes under the so-called “dewpoint” varying between 25° C. and 55° C. (that can vary on the basis ofthe combustible, of the air-combustible mixture and of the CO₂ emitted);under said temperature, vapour contained within the fumes startscondensing, thus yielding a great amount of heat. It is importantunderlying that latent condensation heat is equal to 11% of the totalheat from the methane combustion. For this reason, without anydispersion, a condensation boiler can theoretically have a calorificefficiency of 111% with respect to the calorific power (100% sensitiveheat+11% condensation latent heat).

However, these apparatuses reach very high efficiencies of 103%-106%only if employed in low temperature systems (floor coils) with atemperature of the circulating thermal vector (water) of 35° C.-40° C.,or applying some specific solutions (reducing the temperature and/orflow rate of the thermal vector, limiting the boiler power). Anyway, ifthe temperature of these boilers is kept at a value of 60° C.-80° C.(necessary to make a system with radiators or fan coils workingproperly) the condensation boiler does not succeed recovering thevaporisation latent heat since water inlet temperature is higher or tooclose to the fume dew temperature: in this case, condensation boileroperates as a standard high efficiency boiler (efficiency 85%-95%).

In view of the above, it is suggested according to the present inventionan apparatus permitting to recover part of the sensitive heat and partof the condensation latent heat (also known as vaporisation latent heat)contained within the large vapour amounts produced by the combustion.

Heat recovered by the described apparatus will be used to pre-heat thethermal vector contained within the tubes of the heating system (usuallywater) that, from the final users (radiators, ventilation-convectors,radiating tubes, ecc) enters again within the boiler to be then heatedand sent again to the final users (but it is also possible use the samefor other applications). This permits that the boiler uses less energyto increase the thermal vector at the set temperature, thus obtaining asaving of fuel with the same energy obtained from the system.

Apparatus according to the invention employs a water/fume exchanger witha compression thermodynamic cycle allowing recovering a high amount ofheat until cooling the fumes (even up to about +35° C.) and transferringsaid heat to the thermal vector with a different temperature (evenbeyond +80° C.).

It is therefore specific object of the present invention a boilercondensation module, characterised in that it comprises a water/fumeheat exchanger and a closed circuit compression thermodynamic frigorificapparatus, said module being communicated with a boiler intercepting theflow of the fumes and the flow of the water, in order to subtractsensitive heat and vaporisation latent heat to the fumes of the boilerto yield the same as heat to the system water thus improving thecombustion efficiency.

Preferably, according to the invention, said heat exchanger is of thewater/fume plate or laminar unit type.

Furthermore, according to the invention, said frigorific apparatus is acompression thermodynamic frigorigen apparatus, particularly, comprisedof a fume-refrigerant or evaporator heat exchanger, of an exchanger, ofa refrigerant compressor, of a expansion or lamination member, of acontrol electric-electronic system.

Still according to the invention, said closed circuit compressionthermodynamic frigorific apparatus provides an evaporation temperatureincluded between 12° C. and 20° C. and a condensation temperaturevariable between 50° C. and 95° C.

Particularly, said frigorigen machine comprises one or morewater-refrigerant heat exchanger of the plate and/or laminar unit and/ortube bundle type; one or more fume-refrigerant heat exchangers of theplate and/or laminar unit and/or tube bundle type; one or morecompressors, even of the inverter type, suitable to compress R12, R134,R404, R407, R410, R125 refrigerant fluids and like as heat; one or morelamination members of the capillary and/or thermostatic expansion valvetype, with or without pressure equaliser and/or calibrated choke;metallic tubes connecting the various components.

Furthermore, according to the invention, parts that can be directly intouch with the fume condensate are comprised of material resisting tothe acid corrosion due to the same condensate, e.g. AISI 316L stainlesssteel, or other suitable materials.

Still according to the invention, one or more water/fume plate orlaminar unit type heat exchangers are provided, with or without thethermal exchange with the carburant air.

Further, according to the invention, said water-fume heat exchanger andsaid fume-refrigerant heat exchanger (evaporator for the frigorificcircuit) are installed inside a metallic room within which fumescirculate, realised in such a way that condensate produced by the twoheat exchangers can easily outflow outside said metallic room, avoidingthat a mixing of air, environment, water and fumes occurs.

Furthermore, protection and control fittings are provided, that areusually used in frigorific circuits such as: pressure switches,thermostats, flow-meters, manometers, thermometers, transducers, fumeextractors, passage indicators, fans, liquid injection systems, liquidreceivers and dividers, filters, electric/electronic boards, pressureequalisers and reducers, interception and adjustment valves, mixingvalves, condensate exhaust siphons.

Particularly, fluid R134A is employed as refrigerant fluid, or, asalternative, various refrigerant fluids can be employed (R404; R407,R410 R125) circulating within the frigorific circuit.

Still according to the invention, a volumetric or centrifugal compressorof the hermetic, semi-hermetic or open type is provided.

Always according to the invention, another fluid or a mixture comprisingglycol or another anti-freezing liquid is used instead of water asthermal vector of the system.

Furthermore, according to the invention, transfer (transmission) of theheat recovered from the fumes occurs to the fluid of another system notdirectly connected with the system of the main water, for example forheating the sanitary heat water and/or for feeding another heatingsystem and/or for directly heating air.

Finally, according to the invention, counter current flow heatexchangers can be used.

“Condensation boiler module” according to the present invention aimsobtaining for a standard high efficiency boiler (not a condensationboiler) the same advantages of a condensation boiler (low consumption,very high efficiency and low emissions), and at the same time solvingthe two main drawbacks: high costs and good operation only with lowwater temperature within the system.

Apparatus according to the invention permits recovering condensationlatent heat, even maintaining a high temperature of the thermal vector(60° C.-80° C.). This permits avoiding expensive modifications of thesystem for delivering the thermal vector and of the final devices(radiators-fan coils) that would be necessary in case of installation ofa condensation boiler on an already existing heating system. Only asmall percentage of the existing heating systems is realised with afloor diffusion, while at present 95% of systems are provided with castiron or aluminium radiators, where the provision of a condensationboiler is not convenient.

The present invention will be now described, for illustrative but notlimitative purposes, according to its preferred embodiments, withparticular reference to the figures of the enclosed drawings, wherein:

FIG. 1 is a schematic view of a boiler provided with a condensationmodule according to the invention; and

FIG. 2 particularly shows the condensation module of FIG. 1.

Observing the enclosed figures, it is shown a boiler 1, with acondensation unit 2 according to the invention. As shown in FIG. 1 forexemplificative purposes, module according to the invention can beapplied as outer component according to the scheme boiler 1, boilercondensation module 2, radiators 3, water delivery tubes 4 to the users,water return tubes 5 from the users, boiler fume exit 6, flue 7,condensate exhaust 8.

Observing particularly FIG. 2, it is shown a condensation module 2 for aboiler according to the invention, substantially comprising a water/fumeplate or laminar unit type heat exchanger E and a frigorific apparatusof the compression thermodynamic type.

Said frigorigen apparatus is comprised of a fume-refrigerant orevaporator heat exchanger G (evaporator), of a refrigerant compressor H,of an expansion or lamination member L, of a control electric-electronicsystem and of various functional fittings usually used in the frigorificsystems, that are not specific object of the present invention.

Fumes arriving from the boiler (not shown), enter within the boilercondensation module 2, into the metallic room P through the hole C, at atemperature of about 150° C., meeting in sequence the fume/water heatexchanger E, where, due to the thermal exchange with water, cools up to90° C., and then, the fume-refrigerant heat exchanger G, where they arefurther cooled, since refrigerant circulates at a temperature lower than20° C.

Fumes cool in this heat exchanger G up to about 35° C., thus permittingthat vapour contained in the same condenses with the consequent recoverof the vaporisation latent heat.

Finally, fumes exit from the metallic room P through the hole D,possibly pushed by the fan/extractor N compensating the higher flowresistance and the lack of draft due to the low temperature.

Water coming from the system at about 60° C. enters through joint A,passes first within the water-refrigerant heat exchanger F, thus beingpre-heated up to about 62-64° C. due to the high temperature of therefrigerant (about 110° C.), and then passes within the water-fume heatexchanger E, further heating (possibly up to 64° C.-67° C.), since itexchanges heat with fumes up to 150° C.

Finally, water exits from the boiler condensation module by joint Bthrough tube Q. Under standard conditions, said pre-heated water isdestined to go back into the boiler, that will require less fuel toincrease the temperature just for the previous pre-heating.

Refrigerant (usually R134A or a similar fluid) is contained in awatertight circuit. Compressor H compresses fluid as vapour at apressure (16-22 bar) necessary to obtain that the vapour has the watertemperature when entering again within the final users.

Overheated vapour enters within the water-refrigerant heat exchanger Fthrough the high-pressure tube I; refrigerant yields heat to water, saidwater heating while refrigerant cools under its saturation temperature(referred to its specific pressure) changing state and becoming inliquid form. Now, refrigerant meets the lamination member L, aiming toreduce its pressure (about 3.5-4.5 bar) in order to lower its saturationtemperature (12° C.-18° C.) and at the same time its real temperature.

Thus, refrigerant is in a liquid-vapour saturated mixture state and,through the low pressure tube M, enters within the fume-refrigerant heatexchanger G; here, refrigerant receives heat from fumes (cooling up to35° C.-40° C.) permitting state passage into vapour of the remainingliquid part of the refrigerant. Refrigerant is thus sucked by compressorH to start again the cycle.

“Boiler condensation module” according to the invention can be installedwithin a forced draught boiler or into a blown air burner during itsmanufacturing or it can be provided in an already existing heatingsystem, intercepting boiler fumes and the boiler inlet water tube.

Condensation of fumes occurs only inside the module 2 thus preservingboilers with respect to damages due to the condensate acidity.

It is well evident that recovered heat can be used for different objectswith respect to that or pre-heating water for the boiler.

“Boiler condensation module” according to the invention can be realisedfor different powers in order to be suitable for boilers havingdifferent sizes and employing different fuels. In fact, also the type offuel influences the power of the inventive solution since, with the samelower calorific power, the upper calorific power is not the same.

“Boiler condensation module” according to the invention has theadvantage of transforming a standard boiler into a very high efficiencyboiler thanks to the almost complete recover of the heat (sensitive andlatent heat) usually dispersed into the atmosphere. In fact, withoutwasting energy, consumption of fuel is reduced at the minimum level, aswell as the emissions are proportionally reduced with respect to thereduction of fuel consumption.

Polluting substances are further kept into the condensation water formedduring the operation both because some components are soluble andbecause of the specific surface-active power of the same condensationwater.

By the operation of the system with inlet water warmer than 35° C.,boiler provided with “boiler condensation module” has efficiency higherthan the traditional condensation boilers. Boiler condensation module ischeap and simple to realise and allows obtaining a very interestingperformance/price ratio.

The present invention has been described for illustrative but notlimitative purposes, according to its preferred embodiments, but it isto be understood that modifications and/or changes can be introduced bythose skilled in the art without departing from the relevant scope asdefined in the enclosed claims.

1. Boiler condensation module comprising a water/fume heat exchanger (F)and a closed circuit compression thermodynamic frigorific apparatus (M),said closed circuit compression thermodynamic frigorific apparatuscomprising a fume refrigerant (or evaporator) heat exchanger (4) ands awater-refrigerant heat exchanger (F), said module being communicatedwith a boiler (1) intercepting the flow of the fumes and the flow of thewater, in order to subtract sensitive heat and vaporisation latent heatto the fumes of the boiler to yield the same as heat to the system waterthus improving the combustion efficiency.
 2. Boiler condensation moduleaccording to claim 1, characterised in that said heat exchanger is ofthe water/fume plate or laminar unit type.
 3. Boiler condensation moduleaccording to claim 1 characterised in that said frigorific apparatus isa compression thermodynamic frigorific apparatus.
 4. Boiler condensationmodule according to claim 3, characterised in that said frigorificapparatus further comprises a refrigerant compressor, an expansion orlamination member (4) and a control electric-electronic system. 5.Boiler condensation module according to claim 1, characterised in thatsaid closed circuit compression thermodynamic frigorific apparatusprovides an evaporation temperature included between 12° C. and 20° C.and a condensation temperature variable between 50° and 95° C.
 6. Boilercondensation module according to claim 1, characterised in that saidfrigorigen machine comprises one or more water-refrigerant heatexchanger of the plate and/or laminar unit and/or tube bundle type; oneor more fume-refrigerant heat exchangers of the plate and/or laminarunit and/or tube bundle type; one or more compressors, even of theinverter type, suitable to compress R12, R134, R404, R407, R410, R125refrigerant fluids and the like as heat; one or more lamination membersof the capillary and/or thermostatic expansion valve type, with orwithout pressure equalizer and/or calibrated choke; metallic tubesconnecting the various components.
 7. Boiler condensation moduleaccording to claim 1, characterised in that parts that can be directlyin touch with the fume condensate are comprised of material resisting tothe acid corrosion due to the same condensate, e.g. AISI 316L stainlesssteel, or other suitable materials.
 8. Boiler condensation moduleaccording to claim 1, characterised in that one or more water/fume plateor laminar unit type heat exchangers are provided, with or without thethermal exchange with carburant air.
 9. Boiler condensation module,according to claim 1, characterised in that said water-fume heatexchanger and said fume-refrigerant heat exchanger (evaporator for thefrigorific circuit) are installed inside a metallic room within whichfumes circulate, realised in such a way that condensate produced by thetwo heat exchangers can easily outflow outside said metallic room,avoiding that a mixing of air, environment, water and fumes occurs. 10.Boiler condensation module according to claim 1, characterized in thatFurthermore, protection and control fittings are provided, that areusually used in frigorific circuits such as: pressure switches,thermostats, flow meters, manometers, thermometers, transducers, fumeextractors, passage indicators, fans, liquid injection systems, liquidreceivers and dividers, filters, electric/electronic boards, pressureequalizers and reducers, interception and adjustment valves, mixingvalves, condensate exhaust siphons.
 11. Boiler condensation moduleaccording to claim 1, characterized in that Particularly, fluid R134A isemployed as a refrigerant fluid, or, as an alternative, variousrefrigerant fluids can be employed (R404, R407, R410, 125%) circulatingwithin the frigorific circuit.
 12. Boiler condensation module accordingto claim 1, characterized in that a volumetric or centrifugal compressorof the hermetic, semi-hermetic or open type is provided.
 13. Boilercondensation module according to claim 1, characterized in that anotherfluid or a mixture comprising glycol or another anti-freezing liquid isused instead of water as thermal vector of the system.
 14. Boilercondensation module according to claim 1, characterized in that transfer(transmission) of the heat recovered from the fumes occurs to the fluidof another system not directly connected with the system of the mainwater, for example for heating the sanitary heat water and/or forfeeding another heating system and/or for directly heating air. 15.Boiler condensation module according to claim 1, characterized in thatcounter current flow heat exchangers are used.
 16. (canceled)